Hey all

Been having some serious engine issues with my J-Reg Mk3 1.3 (AAV).

Missing really badly - split vacuum hose - replaced and solved problem

Then found that the crankcase ventilation/rocker breather pipe had fallen to pieces - replaced (arse of a job as no space)

But in the meantime it has developed a really erratic idle. Idles stable but high (no rev counter), but when it gets hot it alternates between revving and then almost stalling in a metronomic fashion.

I'm at a loss - I'm assuming it's the idle control system going mental, but i have no idea where to start.

It's recently had:

• Oil Filter
• Oil
• Disi Cap
• Rotor Arm
• Plugs
• Coil (although original ignition module)
• Compression test- ~180 on all pots

As well as tyres, brakes, exhaust, fuel tank, wheel bearing, track rods, some bodywork...so i've got a lot of time and money invested!

Weirdly, i've noticed that the thottle arm doesn't sit anywhere near the idle control screw when the throttle is closed? Wondering if there is a bodge hiding somewhere.

does anyone have any ideas?

Getting really peed off! - started googling bike carbs to bypass the problem altogether :-) - havnt got the skills or funds though!

Cheers in advance!

Tim

You could try cleaning the throttle body ( there are plenty of posts on here telling you how to do that.)

But as you mention the fact that the fault 'develops' when the engine is hot, I think that you could well have a faulty temperature sender unit, easy to change, and again, plenty of advice on here telling you how to do that.

Please note, this temperature sender is what controls the amount of petrol that goes into the engine, it does NOT mean that the temperature gauge is necessarily reading wrongly.

Regards.

You could try cleaning the throttle body ( there are plenty of posts on here telling you how to do that.)

But as you mention the fact that the fault 'develops' when the engine is hot, I think that you could well have a faulty temperature sender unit, easy to change, and again, plenty of advice on here telling you how to do that.

Please note, this temperature sender is what controls the amount of petrol that goes into the engine, it does NOT mean that the temperature gauge is necessarily reading wrongly.

Regards.

Thanks!

Is the temp sender the blue one below the Disi in this pic? (click to biggerify)

You could try cleaning the throttle body ( there are plenty of posts on here telling you how to do that.)

But as you mention the fact that the fault 'develops' when the engine is hot, I think that you could well have a faulty temperature sender unit, easy to change, and again, plenty of advice on here telling you how to do that.

Please note, this temperature sender is what controls the amount of petrol that goes into the engine, it does NOT mean that the temperature gauge is necessarily reading wrongly.

Regards.

Thanks!

Is the temp sender the blue one below the Disi in this pic? (click to biggerify)

Thats the one, the blue one sends the signal to the ECU, the black one next to it send the signal to the temperature guage on the dash.

Blue sensor is easy to change, unplug, pull the clip out with a pair of pliers, pop the new one in, i found sticking some grease on the seal helps it go in.

Could be a faulty Lambda sensor too but i'd try the temp sensor first.

You could try cleaning the throttle body ( there are plenty of posts on here telling you how to do that.)

But as you mention the fact that the fault 'develops' when the engine is hot, I think that you could well have a faulty temperature sender unit, easy to change, and again, plenty of advice on here telling you how to do that.

Please note, this temperature sender is what controls the amount of petrol that goes into the engine, it does NOT mean that the temperature gauge is necessarily reading wrongly.

Regards.

Thanks!

Is the temp sender the blue one below the Disi in this pic? (click to biggerify)

Thats the one, the blue one sends the signal to the ECU, the black one next to it send the signal to the temperature guage on the dash.

Blue sensor is easy to change, unplug, pull the clip out with a pair of pliers, pop the new one in, i found sticking some grease on the seal helps it go in.

Could be a faulty Lambda sensor too but i'd try the temp sensor first.

Done this now - but wont know if its worked until i sought out the other engine issues!

Question - the old sender had a rubber seal on it, the new one didnt. There is also an O-ring. With the O ring AND rubber seal on the new sender, i couldnt get it in far enough to seat the circlip (even with a smidge of grease and leaning body weight on the sender with a flat piece of wood) but it goes in suspiciously easily with just the O-Ring.

Now i'd assume the new sender would include the seal as the old one is likely to have degraded, but thats just logically minded, not commercially minded :-)

Was planning to run it up to temperature and keep an eye for leaks - but do i need both seals - i'm guessing i do :-)

Cheers

Tim